In sensors of this type the actual sensor element is made from a microchip which is arranged on an electronic circuit board which also carries the rest of the processing circuit of the sensor.
Sensors of this general type typically have two or three bolt openings wherein bolts inserted through the bolt openings facilitate attaching the sensors at an adjacent components whose inclination, rotation, or pivoting shall be measured.
For cost reasons the electronic circuit board in a sensor of this type is typically arranged in a tub shaped plastic housing and typically encased therein by an at least partially curing encasement compound.
The tub shaped plastic housing typically has a flat base side and an open top side extending parallel thereto from which the electronic circuit board is inserted into the recess of the tub shaped housing and encased therein. This open top side can also additionally be closed by a cover placed thereon that is glued down or bolted down.
The problem is that sensors of this type are bolted with their flat side onto a surface that is not completely flat, for example slightly convex or includes small protrusions. This has the consequence that threading the attachment bolts in an tightening them in parts pressure upon the attachment eyelets of the sensor housing in a direction so that a slight warping of the sensor housing can occur since the housing even with subsequent encasement is not stable enough so that forces imparted by the bolting do not cause any deformation.
This almost always applies for a plastic housing and even for a housing made from metal like e.g. aluminum the deformation is a function of the housing dimension. Certainly a height and wall thickness of an aluminum housing of this type can be selected so that the attachment forces do not cause any deformation however there is also a requirement that sensors of this type are additionally be configured as small and light as possible.
When the tub shaped housing deforms this transfers from there onto the at least partially cured encasement compound and from there again to the electronic circuit board and especially the chip which represents the actual sensor element.
However it has been found that an electronic chip of this type is very sensitive also with respect to a very small mechanical loads and also for an only very slightly deformed housing of the sensor measuring results of the sensor are highly distorted.